Development of liquid-phase oxidation processes by use of highly dispersed metal-metal oxide catalysts

使用高度分散的金属-金属氧化物催化剂开发液相氧化工艺

基本信息

批准号：
07555247
负责人：
TATSUMI Takashi
金额：
$ 5.82万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

We aimed at developing new catalyst systems which promote the partical oxidation of hydrocarbons. In the liquid phase conditions we have found that the size of the zeolite TS-1 crystals have a great influence on the activity of the catalyst because of the diffusion limitation of the reactants/products. The V-containing catalyst VS-2 was synthesized and proved to be active in the oxidation terminal carbons as well as internal carbons. By spin trapping experiments the formation of alkyl radical was detected for the alkane oxidation systems catalyzed by VS-2. The utilization of oxygen instead of H_2O_2 was attained by introducing metallic components incorporated inside the metallosilicates ; the catalyst seems to act as a bifunctional system. However, the rate of oxidation decreased with increasing temperature up to > 50ﾟC because of the promotion of the hydeogenolysis of H_2O_2. We have been successful in extending the system to gas phase oxidation. Methane was oxidized to formaldehyde over Pd/TS-1 in the presence of H_2 and O_2. Without addition of H_2 the complete oxidation occurred to give CO_2. Similar formaldehyde synthesis was also carried out over the mesoporous catalysts containing transition metals. Hydrothermally synthesized Mo-containing MCM-41 was found most selective for formaldehyde formation from methance and O_2. Vanadium-containing MCM-41 was active in the deep oxidation of methane. It is to be noted that the hydrothermally synthesized mesoporous metallosilicates were more selective than the mesoporous silicates impregnated with metal salts. The selectivity for formaldehyde was sharply dependent on the pore size of the zeolites/molecular sieves, which was interpreted in terms of the successive decomposition of once formed formaldehyde inside the relatively small pores.

我们的目标是开发促进烃类颗粒氧化的新型催化剂体系，我们发现由于扩散限制，TS-1 沸石晶体的尺寸对催化剂的活性有很大影响。合成了含V催化剂VS-2，并通过自旋捕获实验检测到烷基自由基的形成，并证明其在氧化末端碳和内部碳中具有活性。 VS-2催化的烷烃氧化系统是通过在金属硅酸盐中引入金属组分来实现的，但是，随着温度的升高，氧化速率降低。 > 50°C，因为促进了H_2O_2的加氢分解，我们已经成功地将系统扩展到气相氧化。在H_2和O_2存在下，甲烷被Pd/TS-1氧化成甲醛，在水热合成的Mo-2催化剂上也发生了完全氧化，得到CO_2。发现含有 MCM-41 的化合物对于从含甲烷和 O_2 中形成甲醛最具选择性。 MCM-41 在甲烷的深度氧化中具有活性，值得注意的是，水热合成的介孔金属硅酸盐比用金属盐浸渍的介孔硅酸盐更具选择性。甲醛的选择性很大程度上取决于沸石/沸石的孔径。分子筛，其解释为一旦形成的甲醛在相对较小的分子筛内连续分解毛孔。